Question for @phildunlap: Any support for OPC-UA in the works?
No. Haven't had anyone knocking on our door about OPC-UA in some time. It'd be nice to have, but unlikely to spontaneously be a priority of ours (unless someone persuades the decider with $$$).
I've actually not had an occasion to use the OPC DA module, so I don't know that much about it. I just saw that there is not contextual help for it. The underlying protocol implementation was written by openSCADA and we've been packaging org.openscada.opc version 0.9.0 via maven in the OPC module. It looks like there may be newer versions. It looks like they've not changed that library to support OPC UA from what I saw here: https://openscada.atlassian.net/wiki/spaces/OP/pages/6094892/HowToStartWithUtgard
All I can really see from briefly looking at the code for the data source page in Mango is that the host, domain, username, and password fields bring correct may allow the refresh button to detect the server and populate that drop down if they are correct. Not sure what they would be for Arduino OPC Server, didn't see that readily in the documents I looked at.